Medical science has developed apparatus and processes for remediating constricted blood vessels by implanting a stent that expands a section of the blood vessel and improves blood flow. More recently, medical research has created a filter or strainer for insertion in a blood vessel, in particular the vena cava, to prevent blood clots generated after surgery from circulating and contributing to stroke or heart attack. The stent technology has been accepted medical procedure for many years, and the vascular filter is in the early stage of development and evaluation.
One form of vascular filter is a resilient three dimensional frame that may be collapsed to a narrow form in a carrier for insertion that will expand in the blood vessel when released. In contrast to the stent that hugs the blood vessel wall, the filter spreads across the lumen area within the blood vessel to strain particles from the blood stream, particularly blood clots. By catching blood clots in the filter, typically placed in the vena cava, the blood clots are prevented from causing major problems. At a calculated time after surgery, when post-surgery blood clot formation is assumed to have ceased, the filter is retrieved and the captured blood clots safely removed.
To evaluate the effectiveness of a new medical device such as a vascular filter, a considerable amount of laboratory testing must be done and results evaluated. Different materials and geometries are often compared before conducting clinical trials on animal or human subjects. Such laboratory testing involves pumping a flow of liquid, preferably blood, carrying real or simulated blood clots through a section of a blood vessel with the trial vascular filter in place and results being recorded. Useful non-human blood vessels are from pigs, having similar physiology to humans.
However, blood vessels in general, and pig blood vessels in particular, are opaque. Thus, to properly compare and evaluate the test results, the process of catching blood clots in the vascular filter being tested must be observed and documented, for example by the use of real-time fluoroscopic X-ray equipment. Real-time fluoroscopic X-ray imaging involves directing an X-ray beam through a test device to impinge onto a scintillator that converts the X-rays into energy in the visible spectrum. An advance in fluoroscopic X-ray design is disclosed in detail in U.S. patent application Ser. No. 11/606,453 filed Nov. 30, 2006. Patent application Ser. No. 11/606,453 is incorporated in its entirety herein by reference. As described therein, the fluoroscopic system produces a high resolution image while requiring only a low dose X-ray source. The present invention combines the disclosed high resolution low dose fluoroscopic system with a rotating mechanical actuator to enable non-invasive 360° examination of the vascular filter.